chore(webui): record the surfaces the shared dialog moved

The manifest and the screenshots were older than the surfaces they show. The
shared dialog's frame is 640px wide, and its backdrop changed, so the
screenshots that show it no longer match and the measured surfaces no longer
measure. The recorder wrote what it measured, on Linux, from the branch these
fixes are on.

The manifest is the evidence of the migration: the provider form's surface is
640px wide instead of 1434 and carries two more labels and two more texts, the
plugin MCP form's is 640 instead of 800, and the transcript's diff card is 16px
shorter. The attachment labels the provider form holds below the fold are
inside its surface, which the measurement now says because the dialog's
scrolling body can bring them back into view.

Author: stevenjj33